I'm trying to obtain an instance of a task with the variables as specified in the IN of the workflow.

I have searched here on how to do that but it is still too empty Chapter 17. Remote API.

So I went to the manual here:

Chapter 17. Remote API in search of answers. The issue is that I only see this:

Returns a JaxbProcessInstanceWithVariablesResponse that contains

What is a JaxbProcessInstanceWithVariablesResponse? I know it is the information in XML or JSON (with the correct header) but there's no real definition that I can use to parse them. XML and JSON are very versatile and if the format of a JaxbProcessInstanceWithVariablesResponse changes, my program can easily break (there's no spec on how that object is mapped in XML or JSON).

Given those,
How do I do in order to get a task with the IN variables and not just the task without the said variables (the default)?